Light emitting devices based on nanostructured semiconductors

Light emitting devices based on high-efficiency photoluminescence (PL) fluorescent nanocrystals have been investigated in terms of the generation of light from the structure using a variety of deposition methods. An automated modified layer-by-layer (LbL) self-assembly technique has been employed to produce multilayers of thiol-capped red fluorescing CdTe nanocrystals. Indium- tin-oxide (ITO) and aluminium electrodes were used as the electrodes. Morphological characterization was carried out through Schottky field effect (SFEG) SEM and atomic force microscopy (AFM). The structures built presented clear red electroluminescence (EL) to the naked eye. Turn on voltages were found to be in the range of 3-6 volts while the onset current was in the order of tens of microamperes. The role of structure homogeneity, the presence of pinholes and lifetime extension were features addressed during this investigation. Samples with a lifetime of continuous operation in air longer than 60 minutes and highly stable EL spectra were achieved; EL was visible to the unaided eye, although the brightness was still below the commercial standards and has not yet been qualified

Cathodic and Anodic Material Diffusion in Polymer/Semiconductor-Nanocrystal Composite Devices

In the present day, the information technologies and telecommunications sector continually increase their demand for low cost, low power consumption, high performance electroluminescent devices for display applications. Furthermore, general lighting applications, such as white light and large array colour displays, would also benefit from an increase in the overall efficiency. Several technologies are being investigated to fulfill these needs, such as organic light emitting diodes (OLED), polymeric light emitting diodes (PLED) and field effect emission devices. A new and promising technology is light emitting devices (LEDs) based on nanostructured materials. With organic LEDs (OLEDs) already making an impact on the market in an increasingly large number of applications, hybrid technologies based on organic/inorganic nano-composites are a potential the next step. The incorporation of highefficiency fluorescent semiconductor nanoparticles has been shown to have a beneficial effect on device performance, [1] modify the colour output from the device 2 and provide a simplified route to generation of LED type devices. [3

Fabrication and characterization of red-emitting electroluminescent devices based on thiol-stabilized semiconductor nanocrystals

Thiol-capped CdTe nanocrystals were used to fabricate light-emitting diodes, consisting of an emissive nanocrystal multilayer deposited via layer-by-layer, sandwiched between indium-tin-oxide and aluminum electrodes. The emissive and electrical properties of devices with different numbers of nanocrystal layers were studied. The improved structural homogeneity of the nanocrystal multilayer allowed for stable and repeatable current- and electroluminescence-voltage characteristics. These indicate that both current and electroluminescence are electric-field dependent. Devices were operated under ambient conditions and a clear red-light was detected. The best-performing device shows a peak external efficiency of 0.51% and was measured at 0.35mA/cm2 and 3.3V

First 'Rauisuchian' archosaur (Pseudosuchia, Loricata) for theMiddle Triassic Santacruzodon Assemblage Zone (SantaMaria Supersequence), Rio Grande do Sul State, Brazil

The ‘Rauisuchia’ are a group of Triassic pseudosuchian archosaurs that displayed a near worldwide distribution. In Brazil, their fossils are found only in the Santa Maria Formation (Paraná Basin) of the Rio Grande do Sul State, specifically in the Middle Triassic Dinodontosaurus assemblage zone (AZ) and the Late Triassic Hyperodapedon AZ (Rauisuchus tiradentes). Between these two cenozones is the Santacruzodon AZ (Middle Triassic), whose record was, until now, restricted to non-mammalian cynodonts and the proterochampsian Chanaresuchus bonapartei. Here we present the first occurrence of a rauisuchian archosaur for this cenozone, from the Schoenstatt outcrop, located near the city of Santa Cruz do Sul and propose a new species, based on biostratigraphical evidence and a comparative osteological analysis

Mudança e continuidade: a formulação jamesiana do pensamento como um fluxo

Este artigo discute o projeto de psicologia apresentado por William James no final do século XIX. A exposição tem como pano de fundo o debate que James estabelece com outras teorias psicológicas, particularmente o associacionismo, e destaca suas divergências em relação a elas. As diferenças entre a psicologia jamesiana e o associacionismo são apresentadas através da oposição da noção de pensamento, entendido como um fluxo, e a concepção associacionista do estado mental como composição de elementos independentes. O produto da análise é a crítica ao associacionismo com base na tese da unidade intrínseca de cada pensamento e a indicação das conseqüências teóricas e metodológicas dessa nova formulação.This article discusses the project for psychology presented by William James at the end of the nineteenth century. The exposition is concentrated on James' debate with other psychological theories, notably associationism, and points out his criticism to them. The differences between Jamesian psychology and associationism are shown through the opposition of the concept of thought as a stream and associationist comprehension of mental state as a compound of independent elements. The product of this analysis is the criticism of associationism based on the intrinsic unity of each thought and the indication of the methodological and theoretical implications of this new conception

Imagens do imperialismo: o uso de imagens sobre o imperialismo nos livros didáticos

Orientar o olhar para interpretar fontes visuais constitui um aspecto importante para a construção do saber histórico e da capacidade analítica do mundo visual que cerca o aluno. Além disso, as editoras têm investido em um rico material visual. Portanto, propomos analisar os capítulos sobre o Imperialismo do final do século XIX, em três livros didáticos de História destinados ao Ensino Médio para verificar como estão sendo utilizadas as imagens e se as mesmas dialogam com o texto e com o contexto. Ao final, daremos um relato de experiência pessoal do uso positivo de imagens no ensino de História. Nosso aporte teórico são as obras Visto y no visto, de Peter Burke, O desafio de fazer História com imagens, de Paulo Knauss e Através da Imagem, de Ana Maria Mauad

GUIA DE PESQUISAS: estudos sobre Aritmética, Geometria e Desenho no ensino e na formação de professores dos primeiros anos escolares

Guia elaborado pelo pesquisadores do GHEMAT. Importante publicação que serve como guia para condução de futuras pesquisas.Trata-se de inventário da produção GHEMAT 2013-2017 dos estudos de Aritmética, de Geometria e de Desenho. Para a Aritmética, houve a elaboração do mesmo sob a coordenação da Profa. Dra. Neuza Bertoni Pinto – da Rede Amazônica de Ensino de Ciências e Matemática, com a participação dos Professores Aparecida Rodrigues Silva Duarte (UNIVÁS/MG), Bárbara Winiarski Diesel Novaes (UTFPR), Denise Medina França ( UERJ), Edilene Simões Costa (UFMS), Moysés Gonçalves Siqueira Filho (UFES), Rosemeire Aparecida Soares Borges ( UNIVÁS/MG). Para a Geometria e Desenho outro grupo ocupou-se da tarefa coordenado pela Profa. Dra. Maria Cristina Araújo de Oliveira, da Universidade Federal de Juiz de Fora, MG, com a colaboração dos Professores Eliene Barbosa Lima (UEFS), Inês Angélica Andrade Freire (UESB) , Janice Cassia Lando (UESB) , Iran Abreu Mendes (UFPA), Maria Cecília Bueno Fischer (UFRGS), Diogo Franco Rios (UFPel), Sílvia de Castro de Barros (CEDERJ-CECIERJ EAD), Thiago Neves Mendonça (IFOP), Wanderlei Pires Júnior (IFRO), Andréia Magalhães Dias Almeida (Escola Municipal – JF)

Molecular analysis and associated pathology of beak and feather disease virus isolated in Italy from young Congo African grey parrots (Psittacus erithacus) with an "atypical peracute form" of the disease

This study is the first report on the genetic and pathogenic characterization of beak and feather disease virus (BFDV) occurring in Italy. Twenty BFDV strains isolated in Italy from juvenile Congo African grey parrots (Psittacus erithacus) were investigated. Seventeen strains showed an "atypical peracute form" (aPF) of the disease, and three a chronic form (CF). The birds with aPF had been weaned, were independent as far as food and protection were concerned and apparently were without lesions. The gene coding for the putative coat protein was amplified in all isolates while the BFDV genome was sequenced completely in 10 samples, eight of them belonging to aPF affected birds and two from CF of the disease. All full genomes clustered into the J strain of BFDV, where two new subtypes were identified. Recombination analyses showed evidence of genetic exchanges in two BFDV genomes. In addition, a correlation between viral isolate and origin of the breeding material was shown, while an association between the genetic features of the virus and the clinical form was not observed. Histologically, apoptosis was detected frequently in aPF samples and sporadically in CF samples. Interestingly, BFDV antigens were detected in the nuclei and cytoplasm of such apoptotic cells. The data presented here support the hypothesis that, in the absence of a defined BFDV genetic variant accountable for a specific clinical form of psittacine beak and feather disease, differences in the apoptotic rate between aPF and CF are strictly host related

Proposta de Operadores Genéticos na Seleção de Características de Bases de Dados de Organismos Modelo

O envelhecimento é um processo biológico natural de todos os organismos e vêm sendo muito estudado recentemente. Entretanto, não se sabe ao certo todos os mecanismos que influenciam nesse processo, tanto na longevidade quanto na anti-longevidade. Porém, é certo de que muitas pesquisas estão cada vez mais descobrindo processos biológicos que estão atrelados ao envelhecimento. Um exemplo deles é a restrição calórica que pôde estender a longevidade de muitas espécies

Dnmt3a restrains mast cell inflammatory responses

DNA methylation and specifically the DNA methyltransferase enzyme DNMT3A are involved in the pathogenesis of a variety of hematological diseases and in regulating the function of immune cells. Although altered DNA methylation patterns and mutations in DNMT3A correlate with mast cell proliferative disorders in humans, the role of DNA methylation in mast cell biology is not understood. By using mast cells lacking Dnmt3a, we found that this enzyme is involved in restraining mast cell responses to acute and chronic stimuli, both in vitro and in vivo. The exacerbated mast cell responses observed in the absence of Dnmt3a were recapitulated or enhanced by treatment with the demethylating agent 5-aza-2′-deoxycytidine as well as by down-modulation of Dnmt1 expression, further supporting the role of DNA methylation in regulating mast cell activation. Mechanistically, these effects were in part mediated by the dysregulated expression of the scaffold protein IQGAP2, which is characterized by the ability to regulate a wide variety of biological processes. Altogether, our data demonstrate that DNMT3A and DNA methylation are key modulators of mast cell responsiveness to acute and chronic stimulation